An impulse turbine stage (R=0) has a peak efficiency at the design rotor speed and mass flow. If the mass flow stays constant, but the speed decreases by 20%, estimate the percent change in torque and work rate (unitless, normalized by U^2), and calculate the new value of R. Draw the velocity triangles for both the design condition and the off-design condition. You may assume that at design conditions c_3 is axial.Note that alpha_2 is unchanged, and thus c_2 is unchanged with the drop in speed. Also you can assume that the flow angle leaving the rotor does not change, relative to the rotor.